Effect of using an internal teat sealant at drying-off in cows wintered on forage crops in New Zealand on culling in the dry period and early lactation

AIMS: To determine the impact of treatment with internal teat sealant (ITS) compared to no treatment at drying-off on culling during the dry period and 90 days after calving, for cows wintered on forage crops.

METHODS: In four dairy herds in the South Island of New Zealand, cows with no history of clinical mastitis or somatic cell counts >100,000 cells/mL during the 2015–16 season were randomly assigned to treatment with ITS in each quarter (ITS group) or no treatment (Control group). Cows were otherwise treated similarly, wintered on forage crops and transferred to pasture for calving and lactation. Culling was defined as an unplanned exit from the herd, including cows sold for slaughter, cows slaughtered for salvage value and cows that died on farm. Culls and cull dates were recorded between drying-off and 90 days after calving.

RESULTS: Between drying-off and 90 days after calving 24/491 (4.9%) cows in the ITS group and 45/473 (9.5%) cows in the Control group were culled (RR=0.51; 95% CI=0.75–0.83), and between 30 days before calving and 90 days after calving 20/491 (4.1%) cows in the ITS group and 40/473 (8.5%) cows in the Control group were culled (RR=0.48; 95% CI=0.29–0.81). In the final multivariable logistic regression model, adjusting for dry-period length, cow age, breed and farm, the OR for culling in the study period was 0.43 (95% CI=0.23–0.81) for cows in the ITS compared with the Control group. For a Friesian/Jersey cow, aged 4–8 years, with a dry period of 30–80 days, dried-off without ITS, the probability of culling in the study period was 0.10 (95% CI=0.06–0.16), and for such a cow treated with ITS the probability was 0.05 (95% CI=0.03–0.08).

CONCLUSIONS AND CLINICAL RELEVANCE: In these four herds, the use of ITS at drying-off reduced the incidence of culling between drying-off and 90 days after calving. The use of ITS at drying-off in cows prior to wintering on forage crops may provide additional benefit to farmers through reduced incidence of culling and should be considered in any cost–benefit analysis of its use.     

A latex cryptococcal antigen agglutination test for diagnosis and monitoring of therapy for cryptococcosis

SUMMARY: A latex cryptococcal antigen agglutination test (LCAT) was performed on sera obtained during the first 14 days of treatment from 58 animals (46 cats, 9 dogs, 2 koalas and 1 long billed corella) with cryptococcosis. The same commercial kit was used for all samples, and most serum samples were treated with pronase before testing. Sera from all 58 cases tested positive with the qualitative LCAT protocol (using undiluted sera), while sera from all 26 cats without cryptococcosis tested negative. Titres determined using the quantitative protocol ranged from 1 to 131 072 (median titre between 2048 and 4096), with 57 of 58 cases (including all 8 animals that presented for neurological signs) having titres 2 and thus considered positive according to the manufacturer's recommendations. The LCAT titre was positively correlated with disease severity (r = 0.4169; P = 0.0011), and patients with disseminated skin and/or lymph node involvement had significantly higher titres than those that did not (P = 0.0157). The presence of neurological signs, the species of the patient, concurrent viral disease (in cats) and the biotype of the isolate had no significant association with the LCAT titre. Cats that died of active cryptococcosis despite treatment did not have significantly higher titres (P = 0.3010) than those that responded to treatment. Sequential LCAT determinations obtained in 37 patients during treatment provided a useful quantitative indication of clinical progress, although the decline in titre lagged somewhat behind clinical improvement. Generally, the antigen titre declined by 2 to 4 fold per month during successful therapy. Although there are insufficent data to make unequivocal recommendations, we suggest that either antifungal therapy be continued until the LCAT titre declines to less than 1, or therapy be discontinued after a 32 fold or greater reduction in titre, with periodic monitoring of the serum antigen titre. Treatment of serum samples with pronase substantially increased the sensitivity of the LCAT.     

Antibiotics for the preservation of koala (Phascolarctos cinereus) semen

Aim To determine the normal microbial flora of the koala ejaculate and prepuce in order to select appropriate antibiotics for addition into diluents designed for the preservation of semen.
Procedure Bacteriological samples of the koala prepuce (n = 12) and ejaculate (n = 20) were submitted for microbial culture and sensitivity testing. Microbial flora of ejaculates collected by electroejaculation and artificial vagina were compared. The effects of varying concentrations of penicillin G and gentamicin on sperm motility and on the growth of bacteria in diluted semen stored at room temperature and 16°C over a 24 h period were investigated.
Results A range of bacteria was isolated from the koala prepuce and ejaculate. The predominant organisms in semen collected by electroejaculation and artificial vagina were Corynebacterium spp, none of which could be assigned to any recognised species. The addition of penicillin G and gentamicin to a PBS-based diluent at dose rates of 1000 to 2000 IU/mL and 100 to 200 m g/mL respectively, resulted in no adverse effect on sperm motility over a 24 h incubation period. Penicillin G (1000 IU/mL) and gentamicin (100 m g/mL) prevented growth of bacterial contaminants in diluted koala semen.
Conclusion By controlling the growth of bacteria in extended koala semen, penicillin G and gentamicin are likely to lengthen the period by which spermatozoa can be stored at 16°C and reduce the possibility of disease transmission during artificial insemination procedures.     

Corpus Luteum–Endometrium–Embryo Interactions in the Dairy Cow: Underlying Mechanisms and Clinical Relevance

Conception rates of dairy cows are currently declining at an estimated 1% every year. Approximately, 35% of embryos fail to prevent luteolysis during the first three weeks of gestation. Interactions between the corpus luteum, endometrium and embryo are critical to the successful establishment of pregnancy and inadequacies will result in the mortality of the embryo. For example, as little as a one day delay in the post-ovulatory rise of progesterone has serious consequences for embryo development and survival. Recently, we found that LH support, degree of vascularization and luteal cell steroidogenic capacity were not the major factors responsible for this luteal inadequacy, but are nevertheless essential for luteal development and function. Progesterone acting on its receptor in the endometrium stimulates the production of endometrial secretions on which the free-living embryo is dependent. However, their exact composition and effects of inadequate progesterone remains to be determined. The embryo is recognized through its secretion of interferon tau (IFNT), which suppresses luteolytic pulses of prostaglandin F_2α. In the cow, it is most likely that IFNT inhibits oxytocin receptor up-regulation directly and does not require the prior inhibition of oestrogen receptor α (ESR1). Unravelling the precise luteal-endometrium and embryo interactions is essential for us to understand pregnancy establishment and development of strategies to reverse the declining fertility of dairy cows.     

The Effects of Cryopreservation on the Morphometric Dimensions of Iberian Red Deer (Cervus elaphus hispanicus) Epididymal Sperm Heads

Computer-automated sperm-head morphometry was used in this study to determine the effects of cryopreservation on red deer sperm-head morphometry. Epididymal sperm samples were collected from 40 mature stags and were divided. One portion was diluted at room temperature in a Tris-citrate egg yolk medium, containing 6% glycerol. A microscope slide was prepared from single extended sperm samples prior to freezing. The remainder of each sample was frozen in nitrogen vapours. After thawing, sperm smears were prepared as described above. All slides were air dried and stained with Hemacolor. The sperm-head dimensions for length, width, area, perimeter and shape factor (length/width), for a minimum of 135 spermatozoa were determined for each slide by means of the Sperm-Class Analyser (SCA). Firstly, our results show that cryopreservation substantially reduced (p < 0.001) sperm motility and plasma membrane and acrosome integrities. In addition, sperm heads were significantly smaller in cryopreserved spermatozoa than in the companion extended samples for area (32.05 microm2 vs 32.56 microm2; p < 0.05), length (8.46 microm vs 8.53 microm; p < 0.0001) and shape factor (1.833 vs 1.849; p < 0.0001) for all stags. These differences were found within 29 of 40 stags (75%) for at least three of the morphometric parameters. The individual variability (CV) of sperm head measurements from extended samples was negatively correlated (p < 0.005) with the per cent of change in sperm head measurements after cryopreservation for area (r = -0.465), width (r = -0.483) and perimeter (r = -0.375). Thus, the lower the sperm head variability in the extended samples, the greater the sperm change as a consequence of the cryopreservation. These results suggest that the variability (heterogeneity) in sperm head dimensions of individual stags may be a good indicator of sperm freezability.     

Surgical management of an abdominal abscess in a Malayan tapir

A captive Malayan tapir was observed to have inappetence, weight loss, signs of depression, mild dehydration and diar rhoea. Haematological and serum biochemical tests showed anaemia, hypoproteinaemia, hyperfibrinogenaemia and neu-trophilia with a left shift. Ultrasonic examination of the abdomen under anaesthesia revealed a well-encapsulated abscess. The abscess was marsupialised to the ventral body wall. Culture of the pus produced a mixed bacterial growth. Antimicrobial therapy was based on bacterial sensitivity results. Follow-up ultrasonic examinations showed resolution of the abscess. Ninety-one days after surgery the tapir began regurgitating food and water. An abscess originating from the stomach and occluding the lumen of the duodenum was identified at surgery. The abscess ruptured during surgical manipulations and the tapir was euthanased.